Robust and reliable pumps are in increasing demand for use in the pharmaceutical industry, medicine, automated sampling and processing industrial applications, etc. Miniaturized pumps for transport of liquids through conduits with micro or nano-scale cross-sections are of particular interest in high technology applications like biochip processors, self-contained and/or implantable drug delivery devices. Miniaturized pumps using mechanical parts frequently do not have the required reliability and long term stability of operation which is routinely required in the field of biochips and/or implantable drug delivery devices.
Electrokinetic pumps that operate without moving mechanical parts are known to operate on the principle of Electroosmotic Flow (EOF). Such devices offer improved reliability over mechanical pumps but frequently suffer from impurity sensitivities and limitations pertinent to the requirement to employ chemical surface derivatization to control the polarization of solid surfaces exposed to the pumped liquids. Because of the polarizability induced limitations EOF devices require special attention to the conduit wall materials and conditions on the surfaces immersed in the pumping fluids. This limits the utility of the EOF devices to pumping of compatible fluids only. Frequently, close monitoring and maintenance of pumping fluid temperature and/or pH value ranges is required for the reliable operation of the EOF devices.
In contrast to the EOF electrokinetic micro and nano pumps, pumps in accordance with the current invention utilize for the pumping action only voltages generated by external power supplies. One direct benefit of such arrangement is that the charge induced by the externally applied potentials dominate the resultant electrochemical potentials generated on the device contact surfaces. This allows for utilization of a broad variety of materials in the design and applications of micro-pumps capable to drive transport of a broad spectrum of substances ranging from reactive inorganic solutions to complex compositions and mixtures of biomedicaly relevant materials.